Fluid-tight electrical connection techniques for semiconductor processing

ABSTRACT

A chemical mechanical polishing assembly includes a chemical mechanical polishing system, a fluid source, and a fluid delivery conduit to carry a fluid from the fluid source into the chemical mechanical polishing system. The polishing system has a platen to support a polishing pad, a carrier head to support a substrate and bring the substrate into contact with the polishing pad, and a motor to cause relative motion between platen and the carrier head. The fluid delivery conduit includes a conductive wire extending through an interior of the conduit to flow electrostatic discharge to a ground, and a wire extraction fitting covering and sealing a location where the conductive wire passes through a wall of the fluid delivery conduit.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to U.S. Application No.63/346,811, filed on May 27, 2022, the contents of which are herebyincorporated by reference.

TECHNICAL FIELD

The present disclosure relates to chemical mechanical polishing (CMP),and more particularly to fluid delivery in CMP.

BACKGROUND

An integrated circuit is typically formed on a substrate by thesequential deposition of conductive, semiconductive, or insulativelayers on a semiconductor wafer. A variety of fabrication processesrequire planarization of a layer on the substrate. For example, onefabrication step involves depositing a filler layer over a non-planarsurface and planarizing the filler layer. For certain applications, thefiller layer is planarized until the top surface of a patterned layer isexposed, or until a predetermined thickness of material remains over anunderlying layer.

Chemical mechanical polishing (CMP) is one accepted method ofplanarization. This planarization method typically requires that thesubstrate be mounted on a carrier head. The exposed surface of thesubstrate is typically placed against a rotating polishing pad. Thecarrier head provides a controllable load on the substrate to push itagainst the polishing pad. A polishing slurry with abrasive particles istypically supplied to the surface of the polishing pad. A cleaningfluid, e.g., deionized water, can be sprayed onto the polishing pad toremove debris from the polishing process.

SUMMARY

A chemical mechanical polishing assembly includes a chemical mechanicalpolishing system, a fluid source, and a fluid delivery conduit to carrya fluid from the fluid source into the chemical mechanical polishingsystem. The polishing system has a platen to support a polishing pad, acarrier head to support a substrate and bring the substrate into contactwith the polishing pad, and a motor to cause relative motion betweenplaten and the carrier head. The fluid delivery conduit includes aconductive wire extending through an interior of the conduit to flowelectrostatic discharge to a ground, and a wire extraction fittingcovering and sealing a location where the conductive wire passes througha wall of the fluid delivery conduit.

In another aspect, a method of fabricating a fluid conduit includesplacing a conductive wire through a tubing where the tubing isconfigured to flow a fluid into a chemical mechanical polishingassembly, and coupling the conductive wire to a ground source to form anelectrostatic discharge protective assembly to conduct an electrostaticcharge.

In another aspect, an assembly for electrical connection to a volumehaving a fluid includes a wall that forms a boundary of the volume tocontain the fluid, a conductive wire extending through the volume, andan extraction fitting providing a sealed electrical connection throughthe wall. The extraction fitting includes an annular plastic body havinga passage therethrough. The plastic body has a threaded outer surfacethat is screwed into a threaded aperture in the wall, the conductivewire is inserted into one end of the passage, and a conductive lug isinserted into an opposite end of the passage and contacts the conductivewire. The conductive lug has a threaded outer surface that is screwedinto a threaded portion at the opposite end of the passage.

Possible advantages may include, but are not limited to, one or more ofthe following.

The danger of electrostatic discharge from fluid delivery lines, andthus of damage to fluid delivery lines or other components in a chemicalmechanical polishing system, can be reduced. The components of thegrounding mechanism can be manufactured easily and at low cost. Thefluid flowing through the tubing is not at additional risk ofcontamination when it interacts with a noble metal. Additionally, thesystems and methods disclosed herein are high temperature safe andsemiconductor clean room compatible.

The details of one or more implementations are set forth in theaccompanying drawings and the description below. Other aspects,features, and advantages will be apparent from the description anddrawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view of an example of a polishingstation of the polishing apparatus.

FIG. 2 is a schematic top view of an example polishing station of thechemical mechanical polishing apparatus.

FIG. 3A is a schematic view of a fluid delivery line with a conductivewire in a chemical mechanical polishing system.

FIG. 3B is a schematic cross-sectional view of the fluid delivery lineof FIG. 3A.

FIG. 3C is a schematic cross-sectional view of a ground extractionfitting assembly.

FIG. 4 is a schematic cross-sectional view of a ground extractionfitting assembly attached to a pipe.

FIG. 5 is a schematic cross-sectional view of an electrical connectionextraction fitting assembly attached to a conduit for a semiconductorprocessing system.

FIG. 6 is a schematic cross-sectional view of an electrical connectionextraction fitting assembly attached to a processing chamber of asemiconductor processing system.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

A chemical mechanical polishing system includes a fairly large number offluid delivery lines to deliver a fairly large number of fluids, e.g.,deionized water, steam, nitrogen gas. For example, a typical system caninclude fluid delivery lines to carry slurry to the polishing pad, tocarry cleaning liquid the polishing pad to remove polishing debris, tocarry heated or cooled fluid to the polishing pad to control thetemperature of the polishing process, to carry pressurized gas forpneumatic control of the pressure in a carrier head, etc. Staticelectricity build-up in these fluid delivery lines can caused, e.g., bytribo-electric charging or by electrostatic induction. If the staticelectricity build-up becomes too large, electrostatic discharge canresult, damaging components and tubing along the fluid delivery lines.In particular, static electricity tends to particularly occur in fluidlines that carry hot gas, e.g., steam. The combination of vapor andtemperature can result in tribo-electric charging that is not observedin conventional systems that do not use steam.

A traditional approach for electrostatic dissipative (ESD) tubing is toplace a conductive layer, e.g., of carbon, on the inside of the tubing.However, particles of the material coating the inside of the tubing canbe carried by the fluid to the polishing system, resulting incontamination of and defects on the substrate. Moreover, the polishingenvironment can be humid and wet with splashing slurry, so a conductivelayer on the outside of the tubing can be subject to oxidation orenvironmental wear.

Other commercially available options for grounding techniques, such astubing with integrated carbon impregnated on the inside and outside ofthe tubing, cannot fully dissipate the ESD charge from polymeric fluidlines. Additionally, these methods tend to leak at the ends of thetubing. These problems are exacerbated at high temperatures, anunforeseen problem in chemical mechanical polishing systems, astemperature regulation becomes more important to controlling theprocess.

A wire that is formed of a conductive noble metal and that extendsthrough the interior of the tubing can ameliorate these problems. Noblemetals, such as platinum or gold, do not interact with steam, even athigh temperatures. Thus, placement of a noble metal wire inside thetubing is unlikely to result in particulates and unlikely to causedefects in the integrated circuit product. A ground extraction fittingassembly can be designed to maintain a leak-tight tubing path, whilealso properly introducing a grounding path for the internal noble metalwire. The noble wire can be coupled to a ground source so that thecharge created by the friction between the fluid flow and surroundingpolymeric tubing can be dissipated.

FIGS. 1 and 2 illustrate an example of a polishing system 20 of achemical mechanical polishing system. The polishing system 20 includes arotatable disk-shaped platen 24 on which a polishing pad 30 is situated.The platen 24 is operable to rotate (see arrow A in FIG. 2 ) about anaxis 23. For example, a motor 22 can turn a drive shaft 26 to rotate theplaten 24. The polishing pad 30 can be a two-layer polishing pad with anouter polishing layer 34 and a softer backing layer 32.

The polishing system 20 can include a supply port 40, e.g., at the endof a slurry dispenser arm 43, to dispense a polishing liquid 42, such asan abrasive slurry, onto the polishing pad 30. The polishing liquid 42can be delivered from a reservoir 44 (see FIG. 2 ) through a fluiddelivery line 46, e.g., by a pump.

The polishing system 20 can include a pad conditioner 90 with aconditioner disk 92 (see FIG. 2 ) to maintain the surface roughness ofthe polishing pad 30. The conditioner disk 92 can be positioned in aconditioner head 93 at the end of an arm 94. Pressuring of theconditioner disk 92 against the polishing pad 30 can be controlledpneumatically, e.g., by pressurized gas, e.g., N₂, in a fluid deliveryline 96.

A carrier head 50 is operable to hold a substrate 10 against thepolishing pad 30. The carrier head 50 can also include a retaining ring56 to maintain the lateral position of the substrate 10 below thecarrier head. The carrier head 50 is suspended from a support structure60, e.g., a carousel or a track, and is connected by a drive shaft 62 toa carrier head rotation motor 64 so that the carrier head can rotateabout a central axis 51. Optionally, the carrier head 50 can oscillatelaterally, e.g., on sliders on the carousel, by movement along thetrack, or by rotational oscillation of the carousel itself.

The carrier head 50 can include a flexible membrane 54 having asubstrate mounting surface to contact the back side of the substrate 10,and a plurality of pressurizable chambers 52 a-52 c to apply differentpressures to different zones, e.g., different radial zones, on thesubstrate 10. Pressure to the chambers 52 a-52 c can be controlled bypressure regulators 58 a-58 c. The pressure regulators 58 a-58 c cancouple through pneumatic lines 59 that pass through a rotary union andthe drive shaft 62 and carry pressurized gas, e.g., N₂, to therespective chambers 52 a-52 c.

In operation, the platen is rotated about its central axis 25, and thecarrier head is rotated about its central axis 51 (see arrow B in FIG. 2) and translated laterally (see arrow C in FIG. 2 ) across the topsurface of the polishing pad 30.

As the carrier head 50 and conditioner head 92 sweep across thepolishing pad 30, any exposed surfaces tend to become covered withslurry. For example, slurry can stick to the outer or inner diametersurface of the retaining ring 56. In general, for any surfaces that arenot maintained in a wet condition, the slurry will tend to coagulateand/or dry out, resulting in corrosion of the parts and particulates anddefects on the substrate. One solution is to clean the components, e.g.,the carrier head 50 and conditioner head 92, e.g., with a jet of wateror steam. A carrier head cleaner, e.g., steam treating assembly, for thecarrier head can be part of the load cup in the polishing system.Similarly, a conditioner head cleaner, e.g., a steam treating assembly,for the conditioner head can be part of a conditioner head cleaning cup.In either case, tubing is needed to carry the cleaning fluid, e.g.,liquid water or steam, to the cleaner.

In some implementations, the polishing system 20 includes a temperaturesensor 80 to monitor a temperature in the polishing station or acomponent of/in the polishing station, e.g., the temperature of thepolishing pad 30 and/or polishing liquid 38 on the polishing pad. Forexample, the temperature sensor 80 could be an infrared (IR) sensor,e.g., an IR camera. Alternatively or in addition, the temperature sensorcould be a contact sensor rather than a non-contact sensor. For example,the temperature sensor 80 can be thermocouple or IR thermometerpositioned on or in the platen 24. In addition, the temperature sensor80 can be in direct contact with the polishing pad.

The polishing system 20 can also include a temperature control system100 to control the temperature of the polishing pad 30 and/or polishingliquid 38 on the polishing pad. The temperature control system 100 caninclude a cooling system 102 and/or a heating system 104. At least one,and in some implementations both, of the cooling system 102 and heatingsystem 104 operate by delivering a temperature-controlled medium, e.g.,a liquid, vapor or spray, onto the polishing surface 36 of the polishingpad 30 (or onto a polishing liquid that is already present on thepolishing pad).

As shown in FIG. 1 , an example temperature control system 100 includesone or more arms 110 that extends over the platen 22 and polishing pad30. Multiple nozzles 120 are suspended from or formed in each arm 110,and each nozzle 120 is configured to deliver a temperature control fluidonto the polishing pad 30, e.g., spray the fluid onto the polishing pad.

To operate as a cooling system, the temperature control fluid is acoolant. The coolant be a gas, e.g., air, or a liquid, e.g., water. Thecoolant can be at room temperature or chilled below room temperature,e.g., at 5-15° C. The coolants used in the cooling system 102 caninclude, for example, cold water, liquid nitrogen, or gas formed fromliquid nitrogen and/or dry ice. In some implementations, droplets ofliquid, e.g., water, ethanol or isopropyl alcohol, can be added to a gasflow. In some implementations, the cooling system uses a spray of airand liquid, e.g., an aerosolized spray of liquid, e.g., water. Inparticular, the cooling system can have nozzles that generate anaerosolized spray of water that is chilled below room temperature.

As shown in FIG. 2 , the cooling system 102 can include a source 130 ofliquid coolant medium and/or a source 132 of gas coolant medium. Liquidfrom the source 130 and gas from the source 132 can be carried by tubing134, 136 to and inside the arm 110, before being directed through thenozzle 120, e.g., to form the spray 122. When dispensed, this coolantcan be below room temperature, e.g., from −100 to 20° C., e.g., below 0°C.

Gas, e.g., compressed gas, from the gas source 132 can be connected to avortex tube 133 that can separate the compressed gas into a cold streamand a hot stream, and direct the cold stream to the nozzles 120 onto thepolishing pad 30. In some implementations, the nozzles 120 are the lowerends of vortex tubes that direct a cold stream of compressed gas ontothe polishing pad 30.

To operate as a heating system, the temperature control fluid is aheated fluid. The heating fluid can be a gas, e.g., steam or heated air,or a liquid, e.g., heated water, or a combination of gas and liquid. Theheating fluid is above room temperature, e.g., at 40-120° C., e.g., at90-110° C. The fluid can be water, such as substantially pure de-ionizedwater, or water that includes additives or chemicals. In someimplementations, the heating system uses a spray of steam, or acombination of steam and liquid water. The steam can include additivesor chemicals.

As shown in FIG. 2 , the heating system 104 can include a source 140 ofheated liquid, e.g., hot water, and/or a source 142 of heated gas, e.g.,steam. For example, the source 142 can be boiler. Liquid from the source140 and gas from the source 142 can be carried by tubing 144, 146 to andinside the arm 110, before being directed through the nozzle 120 to formthe spray 122.

Along the direction of rotation of the platen 24, the arm 110 b of theheating system 104 can be positioned between the arm 110 a of thecooling system 102 and the carrier head 70. Along the direction rotationof the platen 24, the arm 110 b of the heating system 104 can bepositioned between the arm 110 a of the cooling system 102 and theslurry dispenser arm 43. For example, the arm 110 a of the coolingsystem 102, the arm 110 b of the heating system 104, the slurrydispenser arm 43 and the carrier head 70 can be positioned in that orderalong the direction rotation of the platen 24.

Rather than separate arms, the temperature control system 100 caninclude a single arm to dispense both the coolant and the heating fluid.

Other techniques can be used by the temperature control system 100, inthe alternative or in addition, to control the temperature of thepolishing process. For example, heated or cooled fluid, e.g., steam orcold water, can be injected into the polishing liquid 42 (e.g., slurry)to raise or lower the temperature of the polishing liquid 42 before thepolishing liquid 42 is dispensed. As another example, resistive heaterscould be supported in the platen 22 to heat the polishing pad 30, and/orin the carrier head 50 to heat the substrate 10.

Moderating the temperature of the slurry and polishing pad duringpolishing of a layer allows for increased interaction betweencharge-carrying abrasives such as cerium oxide. By using temperaturecontrol, the material rate of removal can be beneficially increased byboth modulating the physical parameters of the polishing pad as well asaltering the chemical interaction characteristics between the chargedceria and filler layer.

In some implementations, the controller 90 receives a signal from thetemperature sensor 80 and executes a closed loop control algorithm tocontrol the temperature control system 100, e.g., the flow rate, mixingratio, pressure, or temperature of the coolant or heating fluidrelative, so as to maintain the polishing process at a desiredtemperature.

In some implementations, an in-situ monitoring system measures thepolishing rate for the substrate, and the controller 90 executes aclosed loop control algorithm to control the temperature control system,e.g., the flow rate or temperature of the coolant or heating fluidrelative, so as to maintain the polishing rate at a desired rate.

The polishing system 20 can also include a high pressure rinse system106. The high pressure rinse system 106 includes a plurality of nozzles150, e.g., three to twenty nozzles that direct a cleaning fluid, e.g.,water, at high intensity onto the polishing pad 30 to wash the pad 30and remove used slurry, polishing debris, etc. The cleaning fluid canflow from a source 156 of cleaning fluid, e.g., a reservoir of deionizewater, through tubing 152 to the nozzles 150.

An example rinse system 106 includes an arm 110 c that extends over theplaten 24 and polishing pad 30. Along the direction of rotation of theplaten 24, the arm 110 c of the rinse system 106 can be between the arm110 a of the cooling system 102 and the arm 110 b of the heating system104.

In some implementations, the polishing system 20 includes a wiper bladeor body 170 to evenly distribute the polishing liquid 42 across thepolishing pad 30. Along the direction of rotation of the platen 24, thewiper blade 170 can be between the slurry dispenser 40 and the carrierhead 70.

Although FIG. 2 illustrates separate arms for each subsystem, e.g., theheating system 104, cooling system 102, and rinse system 106, varioussubsystems can be included in a single assembly supported by a commonarm. Various fluid delivery components, e.g., tubing, passages, etc.,can extend inside each body.

FIGS. 3A and 3B illustrate a fluid delivery line 300, which can besuitable for use in a chemical mechanical polishing system, e. g.,polishing system 20. The fluid delivery line 300 can function as thefluid delivery line 44 for the polishing liquid, pneumatic lines 59 forthe carrier head, fluid delivery line 96 for the conditioner head,tubing 134 or 136 for the cooling system, tubing 144 or 146 for theheating system, tubing 152 for the high pressure rinse system, tubingfor carrying pneumatic and/or cleaning fluid to the load cup and/orconditioner cleaner cup, e.g., liquid water or steam, to the cleaner.

The fluid delivery line 300 can be particularly well suited for carryinga hot gas, e. g., steam, as the combination of vapor and hightemperatures can result in a build-up of electrostatic charge that mightnot occur in a room temperature gas or liquid. For example, the fluiddelivery line 300 can be used as the tubing 146 to deliver hot gas, e.g., steam, from the source 142, e. g., the boiler, or as the tubing todeliver steam for the cleaning the carrier head and/or conditioner headin the load cup and/or conditioner cleaner cup.

The fluid delivery line 300 includes a polymer tubing 310, which can bea material that is electrically insulative and resistant to temperaturesof up to 100° C. and is inert to the fluid passing through the fluiddelivery line 300 and inert to the polishing process. For example, thepolymer tubing can be a perfluoroalkoxy alkane (PFA). The polymer tubing310 has an interior channel 312 through which the fluid flows. Thepolymer tubing 310 can have an inlet 314 and an outlet 316 through whichthe fluid will flow. The fluid delivery line 300 can be formed ofmultiple pieces, e.g., one piece with a threaded outers surface isscrewed into another piece with a threaded inner surface. Additionalsealing between the pieces can be provided polytetrafluoroethylene(PTFE) (e.g., Teflon™) tape or a sealing compound. In addition, althoughFIG. 3A illustrates the fluid delivery line 300 as linear, the fluiddelivery line can have one or more bend or curves.

A conductive wire 340 extends through the interior channel 312 of thepolymer tubing 310. This conductive wire 340 can be connected to acommon ground. For example, the conductive wire 340 can be connectedthrough a fluid-tight ground extraction fitting assembly 350 to agrounding wire 342. The conductive wire 340 can be a noble metal, suchgold and platinum. A noble metal, such as platinum or gold, does notinteract with steam, even at high temperature, so the danger ofparticulates and corresponding defects is low. Within the tubing 310 theconductive wire is “bare,” i.e., not coated or covered by an insulativesheath, so that electrostatic charge can be drained away by the wire340. In contrast, the grounding wire 342 can be nearly any wire, e.g., acopper wire with an insulative sheath, e.g., plastic sheath, that isstripped at the connection to the ground extraction fitting assembly350.

The conductive wire 340 need not extend through the fluid inlet andoutlet of the tubing, but can extend along at least a majority, e.g., atleast 50%, e.g., at least 75%, e.g., at least 90%, of the distancebetween the inlet and the outlet. So the ground extraction fittingassembly 342 should be located near, e.g., within the final 10%, e.g.,final 5%, of the distance between the inlet and outlet. This guardsagainst static discharge building along the majority of the fluid path.

FIG. 3A illustrates a fluid delivery line 300 with two ground extractionfitting assemblies 350, and the conductive wire 340 extending betweenand connected to the two ground extraction fitting assemblies 350.However, this is not necessary. In some implementation, a fluid deliveryline 300 could have a single ground extraction fitting assembly 350, andone end of the conductive wire 340 can be attached to the groundextraction fitting assembly 350 while the other end of the conductivewire hangs “loose” in the fluid delivery line 300. In someimplementation, a fluid delivery line 300 could have a single groundextraction fitting assembly 350, and the conductive wire 340 forms aloop within the fluid delivery line 300 with both ends attached to thesample ground extraction fitting assembly 350. The loop in the wire 340can extend through a loop in the fluid delivery line itself.

In some implementations, the ground extraction fitting assembly 350 caninclude a valve with an adjustable inner diameter. The conductive wirecan be fed through the opening through the valve, and then the valve canbe tightened, e.g., by rotation from the outside of the tubing, so thatthe inner surface clamps and is sealed against the conductive wire. Thevalve can be formed of a plastic that is non-reactive to steam and canwithstand high temperatures, e.g., PFA or polytetrafluoroethylene(PTFE).

In some implementations, the ground extraction fitting assembly 350 issimply provided by a finely drilled hole through the tubing. In someimplementations, the hole is just large enough for one or two of thewires to fit through, and insertion of the wire(s) effectively plugs thehole. If necessary, a sealant could be applied where the wire emergesfrom the hole and then cured to reduce the likelihood of leakage. Theend of a wire can be tapered to aid in insertion and guiding of the wirethrough the hole.

In some implementations, the extraction fitting assembly 350 includes aconductive grounding lug that provides the electrical connection to thewire 340.

FIGS. 3C and 4 illustrate a mechanism to connect an external groundingwire 342 to the conductive wire 340 inside the fluid delivery line 300.The ground extraction fitting assembly 350 includes a fitting 352, whichis an annular body having a passage 354 therethrough. In someimplementations, the passage 354 has a narrow portion 354 a and a widerportion 354 b. The interior surface of the wide portion 354 b of thepassage 354 can be threaded.

The fitting 352 can be a plastic material that does not corrode ordissolve under exposure to the fluid, e.g., steam, in the fluid deliveryline 310. For example, the fitting 352 can be polytetrafluoroethylene(PTFE) (e.g., Teflon™). A bottom portion 358 of the outer surface of thefitting 352 is threaded, and is screwed into a corresponding threadedreceiving hole in the tubing 310 to form a seal between the tubing 310and the fitting 352. Additional sealing between the fitting 352 andtubing 310 pieces can be provided polytetrafluoroethylene (PTFE) (e.g.,Teflon™) tape or a sealing compound between the threads.

The conductive wire 340 extends through a lower portion 354 a of thepassage 354 to contact a conductive lug 360 that is inserted into anupper portion 354 b of the passage 354. In some implementations, thefitting 352 is a tapered body, with the lower end being the narrowerside of the taper. In this case, as the fitting 352 is screwed into thetubing 310, the passage 354 is pinched inward (at 355) so that theplastic of the fitting 352 is firm contacts and is sealed around theconductive wire 340. This can form a primary seal to prevent escape offluid in the fluid delivery line 300 through the passage 354.

The lug 360 can have a threaded outer surface 362 that is screwed into acorresponding threaded region 354 c of the upper portion 354 b of thepassage to form a seal between the lug 360 and the fitting 352. This canprovide a secondary seal to prevent escape of fluid through the passage354. Additional sealing between the fitting 352 and tubing 310 piecescan be provided polytetrafluoroethylene (PTFE) (e.g., Teflon™) tape or asealing compound between the threads.

Two lug nuts 356 can be screwed onto the lug 360, and the externalgrounding wire 342 can we wound around the shaft of the lug 360 andcaptured and compressed between the two lug nuts 356.

One technique for assembling the fluid delivery line 300 with theconductive wire 340 is as follows. Initially the conductive wire isinserted and run through the tubing 310. This can be performed beforethe inlet, outlet, and extraction fitting assembly are attached. Forexample, the conductive wire can be secured to a guide tube havingslightly smaller outer diameter than the inner diameter of the interiorchannel 312. This guide tube can be used to guide the conductive wirethrough the tubing 310, e.g., around bends or curves in the tubing 310.

A portion of the conductive wire 340 that extends past the ends of thetubing can then be inserted into the passage 354 in the fitting 352. Thenarrow portion 354 a can be just wide enough for one or two wires to fitthrough, e.g., the wire sits in the narrow portion 354 a in contact withthe sidewalls of the narrow portion 354 a of the passage 354. Theconductive wire 340 can be inserted through passage 354 until the wireextends into the wider portion 354 b of the passage 354. Optionally, ifthe conductive wire 340 extends past the top surface 357 of the fitting352, the wire 350 can be trimmed so that it does not extendsubstantially past that top surface 357, e.g., by no more than 1 mm.

Then a conductive lug 360 is inserted into the wide portion 354 b of thepassage 354. In particular, the conductive lug 360 can have a threadedshaft 362 which is screwed into the threaded wide portion 354 b of thepassage so that the lug 360 makes firm contact and an electricalconnection to the conductive wire 340. The end of the wire 340 can becompressed (at 344) between the bottom of the lug 360 and the bottom ofthe wider portion 354 b of the passage 354 to provide the electricalconnection.

Finally, the fitting 350 can be attached either directly to the tubing312, or to the inlet 314 or outlet 316. In particular, a bottom portion358 of the outer surface of the fitting 350 can be threaded, and can bescrewed into a corresponding threaded receiving hole in the tubing 312,the inlet 314, or the outlet 316 b.

The assembly process can include turning the fluid delivery line 300 inadvance to prevent clumping, overcoming 90° turns, cutting the wiresflush, locking nuts to push on the wires, and taping, e. g., with Teflontape, the locking nuts to secure them.

In some implementations, the dimensions of the PFA tubing can be ⅛ of aninch thick and up to 7 feet long.

This fluid delivery line can provide a ground path for accumulatedcharge, and thus reduce the risk of component damage, while stillremaining compatible with the polishing process.

Although the description above has focused on fluid delivery lines for achemical mechanical polishing system, as shown in FIGS. 5 and 6 , theground extraction fitting assembly 350 could be adapted for other usesas a general conductive circuit extraction fitting assembly when asealed conductive connection is needed between an inner volume 502 of aprocessing system, e.g., a semiconductor processing system 500, and anouter environment 504, particularly where the inner volume 502 containssteam. A semiconductor processing system typically includes a chamber510 and a support 512, e.g., a pedestal, edge-support ring or lift pins,to hold a substrate 10 inside the chamber 510, and a source 514 of gas,e.g., a boiler to generate steam or heated water, or a facility gasline. Examples of processing systems include steam treatment, but alsorapid thermal processing, etching, and deposition systems where steam isneeded either for temperature control of components or as a processinggas.

As shown in FIG. 5 , the connection could be through a wall of a line520 that carries fluid, e.g., steam, from the source 514 to anothercomponent the processing system, e.g., for injection into the processingchamber 512 or to provide temperature control for a component, e.g., awall, support pedestal, etc., in the processing system 500.Alternatively, as shown in FIG. 6 , the connection could be through awall of the processing chamber 510 directly into the interior volume 502of the chamber. In either case, the wire 340′ could be for grounding,but could also be for other electrical purposes, e.g., to carry DC or ACcurrent from a voltage source 530 to an antenna 540, sensor 542, orother component in the inner volume 502, or to carry a signal, e.g., aDC or AC current, from the antenna 540, sensor 542, or other componentin the interior volume 502 to an external monitoring system orcontroller 533.

A number of embodiments of the invention have been described.Nevertheless, it will be understood that various modifications may bemade without departing from the spirit and scope of the invention.Accordingly, other embodiments are within the scope of the followingclaims.

What is claimed is:
 1. An assembly for electrical connection to a volumehaving a fluid, comprising: a wall that forms a boundary of the volumeto contain the fluid; a conductive wire extending through the volume; anextraction fitting providing a sealed electrical connection through thewall, wherein the extraction fitting includes an annular plastic bodyhaving a passage therethrough, the plastic body has a threaded outersurface that is screwed into a threaded aperture in the wall, theconductive wire is inserted into one end of the passage, and aconductive lug is inserted into an opposite end of the passage andcontacts the conductive wire, and the conductive lug has a threadedouter surface that is screwed into a threaded portion at the oppositeend of the passage.
 2. The assembly of claim 1, wherein the plastic bodyis tapered such that the one end of the passage is compressed to form aseal between the conductive wire and an inner surface of the passage. 3.The assembly of claim 1, wherein the passage includes a lower portionextending from the one end and an upper portion extending from theopposite end, and the upper portion is narrower than the lower portion.4. The assembly of claim 3, wherein the conductive wire is compressedbetween a bottom of the lug and a bottom of the upper portion of thepassage.
 5. The assembly of claim 1, further comprising a sealantbetween the threaded outer surface of the plastic body and the threadedaperture in the wall.
 6. The assembly of claim 5, wherein the sealantcomprises polytetrafluoroethylene (PTFE) tape.
 7. The assembly of claim1, further comprising a sealant between the threaded outer surface ofthe lug body and the threaded portion of the passage.
 8. The assembly ofclaim 7, wherein the sealant comprises polytetrafluoroethylene (PTFE)tape.
 9. The assembly of claim 1, wherein the plastic body ispolytetrafluoroethylene (PTFE).
 10. The assembly of claim 1, wherein thewall comprises a plastic.
 11. The assembly of claim 1, wherein the fluidcomprises steam.
 12. The assembly of claim 1, wherein the conductivewire is made from a noble metal.
 13. The assembly of claim 1, whereinthe wall forms a conduit for flow of the fluid to a semiconductorprocessing system.
 14. The assembly of claim 11, wherein the wall formsa processing chamber of a semiconductor processing system.
 15. Theassembly of claim 14, wherein the semiconductor processing systemcomprises a deposition system, etching system, or thermal processingsystem.
 16. The assembly of claim 14, wherein the conductive wire iscoupled to an antenna or sensor inside the processing chamber.
 17. Theassembly of claim 1, comprising a monitoring system or a controller, anda second conductive wire connecting the monitoring system or controllerto the conductive lug.
 18. The assembly of claim 1, comprising a secondconductive wire connecting the conductive lug to electrical ground.